If all goes well, the touch-enabled Windows 8 browser will ship as part of Firefox 26 for the Windows desktop

Mozilla will launch Firefox for Microsoft's Windows 8 "Modern" user interface in mid-December, more than a year after the operating system's launch, according to the open-source developer's planning documents.

Called the "Preview Release," the touch-ready browser will be packaged with Firefox 26 for the Windows desktop. Firefox 26 is slated to ship Dec. 10.

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Work on the browser -- a so-called "Metro-ized" version of Firefox -- will continue up until release, Mozilla said in notes from a planning meeting Wednesday published on its website.

Before the final release of Firefox 26, Mozilla will pair the Modern version with the browser's "Aurora" and "Beta" channel builds, which are to release Sept. 16 and Oct. 28, respectively. At each step, Mozilla will quash bugs and possibly respond to user feedback with changes.

Mozilla started work on a Modern edition of Firefox, one that would run in the user interface (UI) once known as Metro, more than a year ago. The open-source developer released a rough preview in October 2012, several weeks before Microsoft shipped Windows 8.

At the time, Mozilla's schedule claimed that the Firefox app might appear as early as January 2013. In May, the company said its developers would complete Firefox for Modern between Oct. 2, 2013, and March 20, 2014, with mid-November the likeliest date.

Third-party browser makers face unique hurdles in Windows 8. Only the default browser -- which is set by the user -- can run in the Modern UI; during setup, Windows 8 assigns Internet Explorer 10 (IE10) as the default browser; when Windows 8.1 ships in October, IE11 will be set as the default.

Even so, Mozilla has said it's important that it have a Modern browser app to remain competitive. Google, for instance, has had a Windows 8 Modern version of Chrome since June 2012.

Windows RT, the touch-only spin-off designed for tablets, is a different story. Unlike Windows 8, Windows RT bars all third-party developers from accessing the limited "desktop" mode; only Microsoft's programmers can call the APIs there, which they do to power much of the Modern version of IE on the tablet OS.

A year ago Mozilla accused Microsoft of anticompetitive behavior by purposefully blocking others from building browsers that could effectively compete with IE10 on Windows RT. That may be moot at this point, as Windows RT has struggled even more than its bigger brother, Windows 8, and increasingly looks moribund at best, a bad bet by Microsoft at worst.

Firefox for Windows 8's Modern UI puts the address bar at the top, the usual spot for browsers. Microsoft's IE11 stubbornly puts the bar at the bottom.